Nuclear Fusion for Power Generation – More Real Today
SUN’S POWERHOUSE ON EARTH — REAL OR PIPE DREAM???
It is difficult to imagine a time in future when there will be no further need to increase power production in the world. This is because of the following two factors.
a. World population is increase apace. It will be very very long before it stabilizes at a certain level. More human beings means more need for energy.
b. With increasing prosperity, people will need more comforts. This means they will consume more energy directly or indirectly. This is very worrisome as no government would survive if it asks its citizens to limit their energy consumption by curbing their comforts.
So, the craving for energy relentlessly drives the search for new sources of energy. Conventional nuclear energy produced by the fission process is very much in use today, because the technology has reached a very satisfactory level allowing sustained generation at predictable generation cost. However, some issues like disposal of radioactive wastes, security issues arising out of terror threats, and heightened concern for safety have dimmed the prospect of nuclear power produced through the fission process.
This situation compelled the nuclear scientists to see if the nuclear fusion process that provides the sun with its humungous amount of heat can be replicated on earth. A pilot plant, named ITER is presently being built in France. ITER, when completed, will weigh 23,000 tonnes and stand almost 30 metres (98 feet) tall.
This ultra high-tech facility being built at an astronomical cost stretches modern technology to its limits. Such a mammoth undertaking casts doubt on its commercial viability.
The latest to join the race for a working model of the Fusion-based reactor is the American aerospace giant Lockheed Martin. Its team of ace engineers working in the company’s tech research hub Shunk Works feel that a pilot Fusion-based plant can be designed, manufactured and erected in just about a decade time.
Since the 1950s, attempts to replicate the Fusion-based reaction that generates the seemingly inexhaustible supply of heat energy of the sun are being made. The hydrogen bomb was the first successful attempt towards a man-made fusion-based device. But, building a bigger one to generate electric power on a sustained basis have proved to be a formidable task.
A look at the basic differences between the Fission and Fusion processes will throw some light on the complexities of the later technology.
Differences between the two processes …..
Nuclear fusion and nuclear fission are two diametrically different types of energy-producing reactions. The common feature of both processes is that energy is released from high-powered atomic bonds between the particles within the nucleus. The difference are basic. In Fission, the splitting of an atom into two or more smaller ones causes release of enormous amounts of energy. In contrast, in Fusion, the fusing of two or more smaller atoms into a larger one causes the release of the energy.
Comparison between the two processes …...
a. In nature, nuclear fission generally does not occur. Fusion, however, occurs, if not on earth, but on stars like the Sun.
b. As bye-product, Fission produces many highly radioactive particles. Fusion reactions generally does give out any bye-product. Only if, a fission “trigger” is used, radioactive particles will result from that.
c. For a fission reaction to happen, critical mass of the fissile substance and high-speed neutrons are required. For setting off a Fusion reaction, high density, extremely high temperature environment is required.
d. It takes little energy to split two atoms in a fission reaction. For the fusion process, extremely high energy is required to bring two or more protons close enough so that nuclear forces overcome their electrostatic repulsion.
e. The energy released by fission is a million times greater than that released in chemical reactions, but it is a fraction of the energy released by nuclear fusion. The energy released by fusion is three to four times higher than the energy released by fission.
f. For nuclear bomb-making, fission-based bombs are produced. These are known as an atomic bomb or atom bomb. The other type is the hydrogen bomb, which uses a fission reaction to “trigger” a fusion reaction.
d. Fission process is the most commonly used in nuclear power plants. Fusion is still an experimental technology for producing power.
e. Fuel Uranium is the primary fuel used in power plants. For fusion, Hydrogen isotopes (Deuterium and Tritium) are the primary fuel used in experimental fusion power plants. Deuterium is found in abundance in sea water.
Some more facts about the Fusion-based power generation effort …
A Fusion-bsased plant like the ITER is also known as tokamak. A tokamak works by heating light atoms (deuterium and a second hydrogen isotope called tritium) in a circular containment vessel. The temperature is increased to a level where the atoms’ electrons get detached and fly off. What is left behind is a mixture of free electrons and naked atomic nuclei. It is called plama. This plasma is confined within the vessel and then, heated by magnetic field. After it is sufficiently heated, the nuclei within it coalesce creating the helium nuclei and free neutrons. The neutrons then carry further heat generated by this fusion reaction out of the plasma, and that heat is used to generate electricity.
Dr.Tom McGuire leads the Lockheed team. His compact reactor is a big improvement on the existing designs of tokamak reactors. Dr. Mc Guire’s model has a different field design. Therefore, it is more energy-efficient.
That marks a big improvement over the gargantuan ITER. Dr. Mcguire’s brain child — a 100MW reactor can cater to the needs of power 80,000 homes. It will have a shell of about seven metres diameter, and will weigh less than 1,000 tonnes.
Dr McGuire’s design is still on the drawing board. Lockheed Martin’s top management has unveiled plans to have a working prototype running in five years and the first operational reactors in ten years. For success in this venture, Lockheed is scouting for more Fusion experts. They will augment Dr. McGuire’s team. One thing now appears certain — commercial power generation through the fusion process is not a very distant dream.